Related examples of a product employing piezoelectric ceramics include a piezoelectric actuator, a filter, a piezoelectric resonator (including oscillator), an ultrasonic vibrator, an ultrasonic motor, and a piezoelectric sensor. Among these products, since the piezoelectric actuator has a very high response speed, which is about 10−6 second, to an electrical signal, the piezoelectric actuator is used as a piezoelectric actuator for positioning an XY stage of a semiconductor manufacturing apparatus and as a piezoelectric actuator for an inkjet recording head of an inkjet printer.
On the other hand, with the increase in dot density of an inkjet recording head, it is necessary to arrange a piezoelectric actuator used for the inkjet recording head with a high density. Accordingly, there has been suggested a piezoelectric actuator in which individual electrodes are arranged in a matrix on the surface of a piezoelectric body (for example, see JP-A-11-34313).
FIG. 3A is a plan view illustrating a related inkjet recording head which includes the piezoelectric actuator disclosed in JP-A-11-34313, and FIG. 3B is a cross-sectional view taken along Line III-III of FIG. 3A. As shown in the figures, an inkjet recording head 70 used in the inkjet recording apparatus and employing a piezoelectric method has a structure such that a piezoelectric actuator 61 is disposed on a flow channel member 53 in which a plurality of grooves are formed as ink pressurizing chambers 53a and partition walls 53b are formed as walls for partitioning the ink pressurizing chambers 53a. 
In the piezoelectric actuator 61, a piezoelectric ceramic layer 65 and individual electrodes 66 are stacked in this order on a vibrating plate 62 in which a common electrode 64 is formed on a top surface thereof. The individual electrodes 66 are plurally arranged on the surface of the piezoelectric ceramic layer 65, thereby forming a plurality of displacement elements 67. The piezoelectric actuator 61 is attached to the flow channel member 53 so that the ink pressurizing chambers 53a correspond to the individual electrodes 66.
In the inkjet recording head 70, ink in the ink pressuring chambers 53a is pressurized by applying a driving voltage across the common electrode 64 and the individual electrodes 66 and thus vibrating the displacement elements 67, thereby ejecting ink droplets from ink ejecting holes 58 opened in the bottom surface of the flow channel member 53.
In addition, by constructing the inkjet recording head 70 (piezoelectric actuator 61) so that the individual electrodes 66 are arranged on the piezoelectric ceramic layer with a constant pitch to dispose the plurality of displacement elements 67 and to independently control the displacement elements 67, it is possible to contribute to increase in speed and precision of an inkjet printer.
Each individual electrode 66 includes a driving electrode 66a contributing to displacement of the displacement elements 67 and a connection terminal (land) 66b for applying a driving voltage. An external circuit board (not shown) for applying the driving voltage is electrically connected to the connection terminals 66b by means of soldering or pressing contact members.
Since the connection terminals 66b are formed outside the regions of the ink pressurizing chambers 53a, it is considered that the piezoelectric actuator 61 has an excellent deformation characteristic. Further, it is considered that the decrease in the efficiency of deformation is small and the variation of the deformation amount is small.